Histoplasmosis is a virus found in the fungus spores of bird and bat droppings. Most common in humid areas. They attack when the spores are inhaled, such as in a cleanup project. The spores also commonly hide in dirt and soil, and damp areas filled with organic matter. That's why it's very common in barns, caves, and parks. It's not contagious though.
Farmers, infants, construction workers, and landscapers have the highest chance of being attacked. Keep an eye out in old barns, chicken coops, caves, Mississippi, and Ohio river valleys. Symptoms sneak up on the victim, and the victim usually doesn't know until symptoms appear. Symptoms usually appear 3-17 days after exposure. The most common symptom is chest discomfort, a dry cough, and if severe, a skin rash.
This virus can go from mild to severe. If you have a compromised immune system, histoplasmosis can be fatal. It's hard to prevent a disease that's found in the soil, but to be cautious you can spray down soil or barns before you work in them. Usually, histoplasmosis is mild, and doesn't need treatment. See a doctor if you believe you've been attacked by this virus.